Spirit-
Lehman does not list a rake kit option for the C50 or Tramp on their site. The do list a steering stabilizer. I looked there because Im not a Lehman dealer and have not heard of a rake being offered. As far as I know, no one is building a rake for the C50s but if I were you I'd contact Lehman or maybe Timm's Trikes for more info.
Motor Trikes turnkey Honda Shadow 750 trike is somewhat comparable to the 800cc C50 as far as trikes go and there is no EZSteer for them either.
Sorry I couldn't be of more help to you.